Retrieval catheter

ABSTRACT

A retrieval catheter operable by a single clinician that will neither displace a deployed stent nor cause undue trauma to the vascular lumen or lesion. The retrieval catheter may be sized to accommodate both a guidewire and a balloon wire. The retrieval catheter is easy to navigate through tortuous passageways and will cross a previously deployed stent or stent-graft easily with minimal risk of snagging on the deployed stent or stent graft. The sheath and dilator are adapted to allow a guidewire or balloon wire to pass through the walls of both and to allow the sheath and dilator to move axially with respect to each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/864,354, filed Sep. 28, 2007, entitled RETRIEVAL CATHETER, which isherein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to catheters used for retrieving,positioning, or repositioning endoluminal devices located distal oradjacent to a stent or other previously implanted device.

BACKGROUND OF THE INVENTION

The field of endovascular surgery is rapidly becoming an alternative tomore traditional surgeries such as carotid endarterectomy, coronaryartery bypass grafting, aortic aneurysm repair, and vascular grafting.Percutaneous intervention is becoming the primary means forrevascularization in many such procedures. Distal embolization offriable debris from within the diseased conduit remains a risk ofendovascular surgery, potentially involving complications such asmyocardial infarction and ischemia. Devices such as balloon cathetersand embolic filters have been used to control and remove embolic debrisdislodged from arterial walls during endovascular procedures, distal toan interventional procedure site. Percutaneous introduction of thesedevices typically involves access via the femoral artery lumen of thepatient's groin vasculature. An introducer sheath may then be insertedin the wound, followed by a guide catheter that is advanced to the siteto be treated. A guidewire is usually introduced into the lumen of thevasculature and advanced distally, via manipulation by the clinician, tocross the lesion or area of treatment. Then a catheter containing thedevice(s) may be employed to traverse the length of the guidewire to thedesired deployment location. Once the distal protection device isdeployed, the lesion or stenosis is available for treatment.

A common practice for treating the lesion or stenosis is to deploy astent at the target location to increase the lumen size of the vesseland maintain or increase patency. When feeding a guidewire through thelumen of a stent, there is a possibility that the tip of the wire willbecome diverted and/or ensnared by the stent. This possibility increaseswith increasing vessel tortuosity. This problem has been addressedthrough the use of a soft, flexible, floppy tip at the distal end of thewire to improve steerability and reduce the possibility of engaging thestent or peripheral vasculature. However, a flat-tipped catheteradvanced over a guidewire with an inside diameter larger than theoutside diameter of the guidewire, presents a sharp edge to the vesselor stent at the point of tangential contact. The exposure of this edgeincreases with vessel tortuosity and with an increase in differencesbetween the guidewire outside diameter and catheter inside diameter.

Embolic filters and balloons are often deployed by traversing the lesionbeing treated and deploying the device distally. If a balloon wire orembolic filter becomes caught in the patient's vasculature or isotherwise prevented from removal by a stent, such as the device becomingentrapped within the struts of a stent, then the clinician is typicallyrequired to perform higher risk procedures to retrieve them. Theseinclude subjecting the device to greater retrieval forces, and removalthrough invasive surgical techniques. The former increases the risk ofthe device becoming detached from its guidewire or catheter, whereas thelatter exposes the patient to the increased risks of open surgicalextraction. Successful retrieval of these devices in situations otherthan those originally anticipated, without intimal dissection, plaque,hemorrhage, or vessel occlusion, is an important advancement in thefield of interventional endovascular surgery.

SUMMARY OF THE INVENTION

A retrieval catheter assembly is described that may be operated by asingle clinician and upon delivery will neither permanently displace apreviously deployed stent nor cause undue trauma to the vascular lumenor lesion. The retrieval catheter assembly will enable a tubularretrieval sheath to be advanced over a wire between the outside diameterof a deployed stent and the vessel wall, or over a guidewire through thelumen of a stent and retrieve various devices, e.g., filters, balloons,etc. distal to the stent. The retrieval catheter may also enable atubular sheath to be directed through the sidewall of a stent.

The retrieval catheter assembly comprises a sheath having a balloon wireor guidewire exchange port through the sidewall of the sheath and adilator, which is positioned in the sheath lumen. The sheath has a bodywith relatively stiff proximal and distal sections and with a flexiblemiddle section, which aids in the operation of the device. The dilatoris adapted to slide axially relative to the sheath between an extendedposition and a retracted position while a balloon wire or guidewireextends through the exchange port. When the dilator is withdrawn in aproximal direction into the sheath, it provides a space within the lumenof the distal end of the sheath to accommodate a filter or other deviceretrieved by the wire.

The dilator includes a tapered tip, which allows the device to beinserted between the stent and the vasculature for retrieval of devicesdistal to the stent. The tip may be a soft or hard pliablethermoplastic, metal such as stainless steel, or ceramic and will have aradius, which averts snagging on the stent and vasculature. The innerdiameter of the tip is sized to control the clearance between the tipinner diameter and the guidewire outer diameter, which aids in operationof the device.

The catheter assembly preferably includes a hydrophilic and/or alubricious coating applied to the dilator tip and also preferablyapplied to the sheath from tip to the exchange port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of the catheter assembly.

FIG. 1B is a longitudinal cross-sectional view of the catheter assemblytip with guidewire threading tube.

FIG. 1C is a longitudinal cross-sectional view of the catheter assemblytip and relative position of the cooperative opening region during afirst stage of device retrieval.

FIG. 1D is a longitudinal cross-sectional view of the catheter assemblytip and relative position of the cooperative opening region during asecond stage of device retrieval.

FIG. 1E is a longitudinal cross-sectional view of the catheter assemblytip configured to have a slit type cooperative opening extending to themost distal tip of the assembly.

FIG. 2A is a cross-sectional view of a vascular filter in situ, distalto a vascular lesion.

FIG. 2B is a cross-sectional view of a vascular filter in situ, distalto a vascular lesion that has been covered by a deployed stent.

FIG. 2C is a cross-sectional view of a retrieval catheter of prior art.

FIG. 3A is a cross-sectional view of one embodiment of this inventionshowing a step in a method of using the retrieval device in a vascularfilter retrieval procedure.

FIG. 3B is a cross-sectional view of one embodiment of this inventionshowing a second step in a method of using the retrieval device in avascular filter retrieval procedure.

FIG. 3C is a cross-sectional view of one embodiment of this inventionshowing a third step in a method of using the retrieval device in avascular filter retrieval procedure.

FIG. 3D is a cross-sectional view of one embodiment of this inventionshowing a fourth step in a method of using the retrieval device in avascular filter retrieval procedure.

FIG. 4A is a cross-sectional view of an occlusion balloon with theballoon wire positioned between the deployed stent and the vasculature.

FIG. 4B is a cross-sectional view of a retrieval catheter of prior art.

FIG. 4C is a cross-sectional view of one embodiment of the presentretrieval catheter showing a step in a method of using the retrievaldevice in a balloon retrieval procedure.

FIG. 5 is perspective view of one embodiment of the present retrievalcatheter showing the retrieval catheter exiting the lumen of apreviously placed stent through the sidewall of the stent.

DETAILED DESCRIPTION OF THE INVENTION

As noted above, this catheter assembly includes a sheath, dilator andguidewire. FIG. 1A is a perspective view of catheter assembly 20, havinga sheath 22, dilator 24, guidewire threading tube 25, and guidewire 26.Guidewire threading tube 25 may be constructed from a variety ofpolymeric materials such as polyimide. Guidewire threading tube 25 isprovided to aid in the insertion of the guidewire 26 through sheath slot30 and dilator slot 46 (per FIG. 1B), prior to use in a patient. Thisthreading tube 25 is typically removed from catheter assembly 20 priorto insertion into a patient. Also shown in FIG. 1A is the proximal endof the dilator 24, or dilator hub 28 extending from the luer hub 29.

FIG. 1A additionally depicts the distal section 23 of catheter assembly20. FIGS. 1C-1E are longitudinal cross-sections of distal section 23showing a sheath 22, dilator 24, dilator lumen 27, sheath slot 30,dilator slot 46, and guidewire 26. Note the relative distal movement ofsheath 22 and sheath slot 30 with respect to dilator 24 and dilator slot46. The sheath 22 and hubs 28 and 29 may comprise conventional medicalgrade materials such as nylon, acrylonitrile butadiene styrene,polyacrylamide, polycarbonate, polyethylene, polyformaldehyde,polymethylmethacrylate, polypropylene, polytetrafluoroethylene,polytrifluorochlorethylene, polyether block amide or thermoplasticcopolyether, polyvinylchloride, polyurethane, elastomeric organosiliconpolymers, and metals such as stainless steels and nitinol. The sheath 22or dilator 24 may contain either radiopaque markers or containradiopaque materials commonly known in the art.

In one embodiment, the catheter assembly 20 may be used to retrieve apreviously placed vascular filter 32. FIG. 2A illustrates a vascularfilter 32 with filter wire 34 placed within the vasculature 36, distalto a lesion 37. In this application, a stent 38 is placed over thevascular lesion 37 creating a rough, tortuous region across whichvascular filter 32 is to be retracted as shown in FIG. 2B. FIG. 2Cdepicts a retrieval catheter 40 of prior art. Note the relativelyinflexible catheter shaft and the inability of the catheter 40 tomaintain a concentric position within the lumen of the catheter shaft offilter wire 34. Also note the significant difference between catheter 40inner diameter and filter wire 34 outer diameter, creating an openingwhich provides an opportunity for catheter 40 to engage with the stent38.

FIGS. 3A through 3D show sequential cross-sectional views of theretrieval catheter in use. In these figures, the catheter assembly 20 isused to retrieve a previously placed vascular filter 32.

FIG. 3A illustrates an embodiment of the present retrieval catheter withsheath 22 and dilator 24 navigating the rough, tortuous region throughthe stent 38 toward the previously placed vascular filter 32. The sheath22 may be constructed with varying stiffness along the length. Methodsof construction to achieve variable stiffness in a sheath component arewell known in the art and include varying cross sectional profiledimensions and/or wall thickness, changing the hardness or modulus ofthe sheath material, braid modification, and including the use of aremovable stylet or stiffening wire. Additional methods of achievingvariable stiffness in a sheath component are generally taught by U.S.Pat. No. 6,858,024 and U.S. Pat. Appl. No. 2007/0088323 A1. The sheath22 may be made with an outer diameter that would vary depending ontargeted vascular size. For example, a sheath used with a 0.36 mmguidewire would have an outer diameter that ranges from about 1.57 mm to1.62 mm. The sheath 22 inner diameter would also vary with applicationand for use with a 0.36 mm guidewire typically ranges from about 1.22 mmto 1.27 mm.

The sheath 22 includes a slot or aperture 30 functioning as acooperative opening or exchange port through the sidewall of the sheath.The slot 30 may be formed through the side wall of the sheath 22 bymethods known in the art which may include skiving by hand with astraight razor or cutting with a suitable tool. One or both ends of slot30 may be formed to be perpendicular to the longitudinal axis of sheath22. Alternately, one or both ends may be formed to have a taper toreduce the angle between the proximal end of slot 30 and the guidewire26. As shown in FIG. 3A, the slot 30 may be a formed to have a length 42that would vary with application but would preferably range from about0.20 mm to 0.38 mm. Slot 30 may have a width 44 suitable to provideadequate clearance between the slot 30 and a guidewire 26 or balloonwire. Alternately, slot 30 may be formed as a slit thus providing aninterference fit between the guidewire 26 or balloon wire and the slitwalls. Slot 30 may also be configured with features to provide positivetactile feedback to a user during device use. These may include suchfeatures slot 30 being formed to have a barbell shape that providesstops at the proximal and distal ends of slot 30 for securing guidewire26 or a balloon wire. Slot 30 may also be provided with rough surfacesor serrations along the edge of the slot 30 to provide enhanced tactilefeedback. The slot 30 may be cut at a distance from the distal end ofthe sheath from about 1 cm to about 50 cm from the distal end of thesheath 22 depending on the specific design requirements. Preferably, therange would be from about 5 cm to about 31 cm from the distal end of thesheath 22. The most preferred range would be from about 25 cm to about32 cm from the distal end of the sheath 22.

The outer surface of sheath 22 may be provided with ahydrophilic/lubricious coating. The coating may be applied to the entireouter surface of the sheath. Most preferably, the coating may be appliedfrom the most distal end continuing to about the slot 30 or aperture.The inner surface of sheath 22 component may be provided with ahydrophilic/lubricious coating. The coating may be applied to the entireinner surface of the sheath 22. Preferably, the coating may be appliedto the distal most 40 cm of the sheath 22. Most preferably, the coatingmay be applied to the distal most 30 cm of the sheath 22. The coatingmay be any biocompatible polymer lubricant as commonly known in the art.

Dilator 24 is typically formed from a lubricious plastic material suchas polytetrafluoroethylene, polyethylene, polyether block amide orthermoplastic copolyether to provide a high degree of lubricity in theblood vessel as well as with respect to movement of the sheath 22 overthe dilator 24. Dilator 24 may also be formed of a lubricious plasticmaterial in combination with a metal hypo tube. Dilator 24 is typicallyprovided with a hub 28 at its proximal end and is of a length slightlygreater than the length of the catheter assembly so that when the hub 28of the dilator is advanced fully distally against the proximal end ofcatheter hub 29, the tip of dilator 24 will project beyond the distalend of the catheter. Thus, the length of dilator 24 will depend on thelength of the sheath 22. The tip of dilator 24 is considered to be thetapered portion located at the distal most tip of dilator 24. A lengthof about 1 cm for the tapered portion will be applicable to mostapplications but could range from about 1 mm to 5 cm.

Dilator 24 may be made with an outer diameter sized to pass through thelumen of the sheath 22 with which it is intended to be and may besupplied in various sizes dependent on the application and cathetersheath inner diameter. A typical range of outer diameters for theintended application of retrieving a vascular filter or balloon would befrom about 1.14 mm to 1.19 mm. The clearance between a guidewire 26 orballoon wire and the lumen of dilator 24 is relatively small and wouldvary dependent on intended use. For the intended application involvinguse over a guidewire, a typical inner tip diameter would be from about0.38 mm to 0.43 mm. Alternately, dilator 24 may be used with a balloonwire where a typical inner tip diameter would be from about 0.48 mm to0.53 mm. Dilator 24 has a lumen 27 adapted for passage of a guidewire orballoon wire. Diameters of dilator lumens 27 will vary with intendeduse. A typical dilator lumen 27, suitable for use with a guidewire 26,would be from about 0.48 mm to 0.53 mm. Alternately, dilator 24 may bemade with a lumen 27 suitable for balloon wires, typically ranging fromabout 0.61 mm to 0.66 mm.

Dilator 24 may have a tip made of pliable thermoplastic such as Pebax®(polyether block amide or thermoplastic copolyether from Arkema,Beaumont Tex. 77704) or metal such as stainless steel, nitinol or anyother material with appropriate stiffness, hardness and other propertiessuitable for use in the human body. The dilator tip may alternately beconstructed of a combination of a biocompatible metal and thermoplasticin a variety of ways. The tip may also be of composite metal or ceramicand/or polymer construction.

As shown in FIG. 3A (and similar to the slot 30 through the sidewall ofsheath 22), dilator 24 has a slot 46 through the sidewall of the dilator24. The dilator slot 46 may be formed through the sidewall of thedilator 24 by methods well known in the art which may include skiving byhand with a straight razor cutting with a suitable tool. One or bothends of dilator slot 46 may be formed to be perpendicular to thelongitudinal axis of dilator 24. Alternately, one or both ends may beformed to have a taper to reduce the angle between the proximal end ofdilator slot 46 and the guidewire 26.

The dilator slot 46 may have a length 48 extending from about 1 cmproximal to the dilator tip to the distal end of the luer hub 29.Preferably, the dilator slot 46 may extend from about 1 cm proximal tothe dilator tip to about 100 cm proximal to the tip. Most preferably,the dilator slot 46 may extend from about 1 cm proximal to the dilatortip to about 33 cm proximal to the tip. In still another embodiment,dilator slot 46 (particularly if configured as a slit as describedbelow) may extend from the tip to about, for example, 33 cm proximal tothe tip.

Dilator slot 46 may have a width 48 suitable to provide adequateclearance between the dilator slot 46 and a guidewire 26 or balloonwire. Alternately, dilator slot 46 may be formed as a slit thusproviding an interference fit between the guidewire 26 or balloon wireand the slit walls. Dilator slot 46 may also be configured with featuresto provide positive tactile feedback to a user during device use. Thesemay include such features dilator slot 46 being formed to have a barbellshape that provides stops at the proximal and distal ends of dilatorslot 46 for securing guidewire 26 or a balloon wire. Dilator slot 46 mayalso be provided with rough surfaces or serrations along the edge the ofdilator slot 46 to provide enhanced tactile feedback.

FIG. 3B shows the distal end of the catheter assembly 20 positioned invasculature 36 in close proximity to a previously placed vascular filter32. The catheter assembly 20 was advanced over the previously placedvascular filter wire 34. Note that dilator 24 protrudes from the sheath22.

As shown in FIG. 3C, the dilator 24 is retracted into sheath 22 in thedirection as shown by arrow 50. Note the axial sliding movement of slot30 and dilator slot 46 with respect to slot 30 of sheath 22.

As shown in FIG. 3D, the dilator 24 remains retracted into the sheath22. Sheath 22 is advanced in the direction as shown by arrow 52 therebycollapsing the vascular filter 32. After the filter 32 has beencollapsed and contained within the sheath 22, the catheter assembly 20is withdrawn from the target site.

FIGS. 4A through 4C show sequential cross-sectional views of a retrievalcatheter in use retrieving a balloon 54.

FIG. 4A shows a stent 38 deployed over a balloon 54 and balloon wire 56,trapping the balloon 54 and/or balloon wire 56 between the stent 38 andvasculature 36.

FIG. 4B depicts a retrieval catheter 40 of prior art. Note therelatively inflexible catheter shaft and the inability of the catheter40 to maintain a concentric position within the lumen of the cathetershaft of balloon wire 56.

FIG. 4C illustrates an embodiment of the invention with sheath 22 anddilator 24 navigating the rough tortuous region between the stent 38 andthe vasculature 36 toward the trapped balloon 54. The remainder of theballoon retrieval procedure is similar to the procedure described inFIGS. 3B through 3D.

The present invention may also be used to position or reposition adevice located distal or adjacent to a stent or other previouslyimplanted device. FIG. 5 depicts an embodiment of the present inventionwith sheath 22 and dilator 24 exiting the lumen of a previously placedstent 38 through the sidewall of the stent 38. This embodiment could beused to deploy or reposition an endoluminal device into the branchvasculature. The same embodiment could alternately be used to retrievean endoluminal device from branch vasculature.

EXAMPLES

To construct a sheath, a 1.24 mm PTFE coated mandrel was loaded with a1.29 mm inner diameter etched PTFE liner (1.29 mm inner diameter.×0.02mm thick wall) and secured. A braided sleeving (0.25 mm×0.76 mmstainless steel flat wire, 2 over 2 under, 50 ppi) was loaded andsecured at the proximal end of mandrel. The braid was stretched to thedistal end of the mandrel and carefully trimmed to length with scissorsso that the ends of the wires were uniform. Trimming of the braid lengthmay be achieved with any suitable cutting or trimming tool. A markerband (platinum/iridium, 1 mm width minimum, inner diameter 14.7 mm, 0.25mm minimum thickness) was slid onto the assembly from the proximal endof the loaded mandrel to the distal end. The marker band was carefullybrought up to the end of the braid so that the marker band covered theend of the braid and so that no ends of wires were showing at the markerband. The location of the marker band should be from about 5.08 cm to6.35 cm from the distal end of the mandrel. A hand crimper tool was usedto secure the marker band. The braid was then stretched from theproximal end of the mandrel and re-secured.

To pre-assemble the proximal and distal body stock components of thesheath, the proximal component (Pebax® 7233, 72 durometer and 1.57 mminner diameter and 0.10 mm wall, gold pigment) was cut to about 125 cmand the distal body stock component (Pebax® 5533, 55 durometer and 0.157cm inner diameter and 0.10 mm wall, grey pigment) was cut to about 32.5cm. The distal body stock component was flared with the end of a pair ofsmall tweezers so that it would slide over the proximal body stockcomponent. The distal and proximal components were loaded onto a 0.15 mmPTFE mandrel (nonporous PTFE) and the two components were overlapped by1 mm. A 2.54 cm long length of FEP heat shrink (EP4587-10T, Zeus,Orangeburg, S.C. 29116) was positioned over the center of the 1 mmoverlap of the two body stock components and a heat gun was used to bondthe two components together. The FEP heat shrink tube was removed afterthe bond had cooled.

The pre-assembled body stock component was loaded onto the proximal endof the 1.24 mm PTFE coated mandrel bringing the end of the pre-assembledbody stock component to within 2 cm to 3 cm past the marker band. A heatshrink tube (EP4587-10T FEP 1.9 mm minimum expanded inner diameter) wasloaded over the entire assembly with the end of the heat shrink tubereaching the end of the pre-assembled body stock component distal end.The two ends were bonded together with a heat gun. The assembly washeated in a convection heat shrink reflow oven. The assembly was allowedto air cool, the heat shrink tube was removed and the ends were trimmedwith a razor. The entire assembly was removed from the mandrel. Theassembly was cut to a length of about 142 cm and the tip was trimmed. Ahole was hand cut at about 29.7 cm from the distal end of the sheath. Afemale luer hub (Qosina part No. 41426 Qosina, Edgewood, N.Y. 11717) wasbonded to the proximal end with adhesive (Loctite® 4011 Adhesive, HenkelCorp., Rocky Hill, Conn. 06067).

A stock dilator (Pebax® 7233, light grey pigment, 0.48 mm innerdiameter×1.2 mm outer diameter) was tipped down to 0.36 mm innerdiameter and 0.66 mm outer diameter with a radio frequency tippingmachine (Ameritherm Inc., Scottsville, N.Y. 14546). The dilator was thencut to about 152 cm in length. Any appropriate cutting method may beused. A 4.0 cm slot was hand skived in the dilator starting at about27.2 cm from the distal end of the dilator. The proximal end of thedilator was heat flared to form a mechanical anchor. A female luer hub(Qosina part. No. 64018) was bonded onto the dilator proximal end withLoctite® 3311 Adhesive.

To assemble the catheter assembly 20, a hemostasis valve (part No.RV0317-000, Qosina part No. 88416) was attached to the hub of thedilator 24. With the aid of a 0.36 mm guidewire, the sheath 22 anddilator 24 components were assembled and guidewire threading tube 25(Phelps Dodge part No. Polyimide EP4649-10Z 0.38 mm inner diameter×0.47mm outer diameter, Phelps Dodge HPC, Trenton, Ga. 30752) was installedin the assembly. The catheter assembly 20 was masked to expose theproximal and distal ends. A flexible mandrel (0.46 mm outer diameter)was inserted into the distal end of the assembly until it exited thecooperative opening 30. The loaded assembly was then placed into avacuum plasma system. The entire assembly was plasma treated to enhanceattachment of the polymer lubricant. The catheter assembly 20 wasremoved from plasma system. The sheath 22 and dilator 24 components ofthe catheter assembly 20 were then dip coated with a biocompatiblepolymer lubricant to reduce friction. The catheter assembly 20 withlubricious coating was then heat cured. The flexible mandrel was removedand catheter assembly 20 was then placed in a protective polymer coiland packaged for shipment.

While particular embodiments of the present invention have beenillustrated and described herein, the present invention should not belimited to such illustrations and descriptions. It should be apparentthat changes and modifications may be incorporated and embodied as partof the present invention within the scope of the following claims.

We claim:
 1. A catheter assembly, comprising: a sheath having a sheathsidewall and a sheath exchange port through the sidewall, the sheathexchange port having a first longitudinal dimension; and a dilatorhaving a dilator sidewall, a distal end, and a dilator exchange portthrough the dilator sidewall, the dilator exchange port extendingproximally from the distal end and having a second longitudinaldimension that is greater than the first longitudinal dimension of thesheath exchange port, the dilator slidably positioned in the sheath withthe sheath exchange port and the dilator exchange port aligned to oneanother such that the dilator and sheath are slidable relative to oneanother between an extended position and a retracted position while aguidewire extends through the sheath exchange port and dilator exchangeport.
 2. The catheter assembly of claim 1, wherein the dilator exchangeport is a longitudinally oriented slot that extends from a proximal endof the dilator to the distal end of the dilator.
 3. The catheterassembly of claim 1, further comprising a filter received in a distalend of the sheath.
 4. The catheter assembly of claim 1, furthercomprising a balloon received in a distal end of the sheath.
 5. Thecatheter assembly of claim 1, further comprising a guidewire receivedthrough the sheath exchange port and the dilator exchange port.
 6. Thecatheter assembly of claim 1, further comprising a guidewire having alength wherein a portion of the length is contained within a guidewirethreading tube, the guidewire extending through the distal end of thedilator, the sheath exchange port, and the dilator exchange port.
 7. Thecatheter assembly of claim 1, wherein the dilator and the sheath aremovable axially with respect to each other for a length at least equalto the length of the dilator exchange port, and further wherein whenmoved along the length of the dilator exchange port, the dilator and thesheath move from a first axial positional relationship in which thedistal end of the dilator extends beyond a distal end of the sheath, toa second axial positional relationship in which the distal end of thesheath extends beyond the distal end of the dilator.
 8. The catheterassembly of claim 1, wherein the dilator comprises a lubricious plasticmaterial.
 9. A method of retrieving a first endoluminal device locateddistal to a second endoluminal device, wherein a guidewire extendsproximally from the first endoluminal device past the second endoluminaldevice and beyond to a proximal end of the guidewire extending out of apatient's body, the method comprising: providing a catheter assemblycomprising an inner and an outer tube fitted around the inner tube, bothtubes having walls with openings through the walls and distal ends withdistal end openings, wherein the openings are provided through the wallsof both tubes in cooperative relationship to allow a guidewire to passthrough the walls of both tubes and wherein the inner and outer tubesare movable axially with respect to each other; positioning the distalend of the inner tube so that it extends distally beyond the distal endof the outer tube; inserting the proximal end of the guidewire into thedistal end of the inner tube and continuing to pass the guidewirethrough the inner tube until the proximal end of the guidewire extendsthrough the openings through the walls of both tubes; passing thecatheter assembly in a distal direction over the guidewire until thedistal ends of the inner tube and outer tube have passed beyond thesecond endoluminal device and the distal end of the inner tube islocated proximal to the first endoluminal device; positioning the distalend of the outer tube so that it extends distally beyond the distal endof the inner tube; moving the distal end opening of the outer tube withrespect to the first endoluminal device to cause the first endoluminaldevice to enter the distal end opening of the outer tube and reside inthe distal end of the outer tube; and withdrawing the catheter.
 10. Amethod of retrieving a first endoluminal device through a sidewall of asecond endoluminal device, the method comprising: providing a catheterassembly comprising an inner and an outer tube fitted around the outertube, both tubes having walls with openings through the walls and distalends with distal end openings, wherein the openings are provided throughthe walls of both tubes in cooperative relationship to allow a guidewireto pass through the walls of both tubes and wherein the inner and outertubes are movable axially with respect to each other; and positioningthe distal end of the inner tube so that it extends distally beyond thedistal end of the outer tube; and inserting the proximal end of theguidewire into the distal end of the inner tube and continuing to passthe guidewire through the inner tube until the proximal end of theguidewire extends through the openings through the walls of both tubes;and inserting the catheter assembly through the sidewall of the secondendoluminal device; and passing the catheter assembly in a distaldirection over the guidewire until the distal ends of the inner tube andouter tube have passed beyond the second endoluminal device and thedistal end of the inner tube is located proximal to the firstendoluminal device; and positioning the distal end of the outer tube sothat it extends distally beyond the distal end of the inner tube; andmoving the distal end opening of the outer tube with respect to thefirst endoluminal device to cause the first endoluminal device to enterthe distal end opening of the outer tube and reside in the distal end ofthe outer tube; and withdrawing the catheter.
 11. A method of retrievingan endoluminal device, the method comprising: receiving a guidewire in acatheter assembly, the catheter assembly comprising a sheath having asheath sidewall and a sheath exchange port through the sidewall, thesheath exchange port having a first longitudinal dimension and a dilatorhaving a dilator sidewall, a distal end, and a dilator exchange portthrough the dilator sidewall; retracting the distal end of the dilatorinto the sheath while the guidewire is received through the sheathexchange port and the dilator exchange port; retrieving the endoluminaldevice into the sheath and distal to the dilator; and retrieving thecatheter assembly and the endoluminal device.
 12. The method of claim11, wherein the dilator exchange port is a longitudinally oriented slotthat extends from a proximal end of the dilator to the distal end of thedilator.
 13. The method of claim 11, wherein the endoluminal deviceincludes a filter that is retrieved into the sheath.
 14. The method ofclaim 11, wherein the endoluminal device includes a balloon that isretrieved into the sheath.
 15. The method of claim 11, furthercomprising delivering the catheter assembly to an endoluminal locationwithin a body of a patient over the guidewire.
 16. The method of claim11, further comprising extending the guidewire through the distal end ofthe dilator.
 17. The method of claim 11, wherein the dilator and thesheath are moved axially with respect to each other for a length atleast equal to a length of the dilator exchange port, and furtherwherein when moved along the length of the dilator exchange port.